3. 7 out of 9 writers on the show are women.

4. Jon Hamm could have become famous for playing Jack Donaghy instead.

Can you imagine Mad Men without Jon Hamm? Or 30 Rock without Alec Baldwin? In 2009, Hamm told Entertainment Weekly that “I actually auditioned for the role of Jack Donaghy. … It was way early in the process. So somewhere on tape, there exists me talking about three kinds of heat.”

5. Mona, Roger Sterling’s ex-wife, is John Slattery’s wife in real life.

6. The toxic smog featured in the episode “Dark Shadows” really happened.

Megan tells Don, “The radio said there’s a smog emergency. The air’s toxic. I don’t want that in here.” In the world Matthew Weiner’s created, this is less about the historical reference point and much more about symbolism, however, the smog did cause real problems for real New Yorkers of the time.

The smoggiest day the city experienced that year was on November 24th (in Mad Men it’s mentioned as Megan is preparing Thanksgiving dinner), and there are varying reports that the smog killed anywhere from 169 to 400 people in the city that year.

16. The show paid $250K to use The Beatles iconic song “Tomorrow Never Knows” in an episode.

Weiner told the times, “It was always my feeling that the show lacked a certain authenticity because we never could have an actual master recording of the Beatles performing. It always felt to me like a flaw. Because they are the band, probably, of the 20th century.”

17. Robert Morse starred in the original 1967 movie “How to Succeed in Business Without Really Trying”

21. Much of season 3 revolves around a commercial parody of “Bye Bye Birdie” – the nickname Don has for Betty. By the end of the season, they divorced.

22. In real life, Vincent Kartheiser lives “off the grid”.

In an interview with The Guardian, the man who plays Pete Campbell suggested that he doesn’t have much money, a TV, or even a toilet:

I have been in a slow process of selling and giving away everything I own. Like, I don’t have a toilet at the moment. My house is just a wooden box. I mean I am planning to get a toilet at some point. But for now I have to go to the neighbours. I threw it all out.